Conventional vacuum switchgear exists for the purpose of providing high voltage fault interruption. Examples of such vacuum switchgear include vacuum fault interrupters (also referred to as “vacuum interrupters” or “interrupters”), which generally include a stationary electrode assembly having an electrical contact, and a movable electrode assembly on a common longitudinal axis with respect to the stationary electrode assembly and having its own electrical contact. The movable electrode assembly generally moves along the common longitudinal axis such that the electrical contacts come into and out of contact with one another. In this way, vacuum interrupters placed in a current path can be used to interrupt extremely high current, and thereby prevent damage to an external circuit.
Such a vacuum interrupter may be encapsulated in a rigid or semi-rigid structure that is designed to provide insulation to the interrupter. The rigid structure may be designed to encapsulate one or more air cavities, in addition to the vacuum interrupter and related components. The air cavities may be used to facilitate construction and/or operation of the vacuum interrupter and its encapsulating structure. For example, such an air cavity may provide space for movement of various components, or may allow thermal expansion of one or more materials associated with making or using the vacuum interrupter.